1. Field of the Invention
The present invention is generally directed to the field of cooking grease storage devices. More specifically, the present invention is directed to a heated grease storage tank that is substantially comprised of an plastic material such as, for example, polyethylene. Preferably the plastic material is transparent or at least semi-transparent.
2. Description of the Related Art
It is well-known that the use of cooking oil for frying food in the food service industry has required that restaurants provide systems and methods for storing used cooking oils so that that the oil and grease may be subsequently recycled. Up until the mid-1980's standard recycling equipment was the 55 gallon barrel. This equipment was improved in the 1970's by the provision of a cosmetic, metal cabinet enclosure to encase the barrels.
In 1983 Don Onken of Onken Enterprises introduced the bulk tank storage method of collection to the rendering industry. This collection method tripled route capacity and reduced processing costs by bulking the material collected in the truck. During the 1990's, automated grease handling systems were developed which automated a number of the steps involved in the recycling of fats from the fryer to the recycling plant.
These alternate solutions typically placed the grease and used cooking oil in a heated storage tank usually located inside the restaurant kitchen. The grease and used cooking oil located within the storage tank were transferred to a truck by through-the-exterior-wall connections. During storage it is necessary to maintain the grease at a warm temperature so that it readily will flow through the evacuation plumbing to the collection truck. It is also necessary to have a reliable means for monitoring the remaining capacity of the storage tank to avoid over-filling it.
U.S. Pat. No. 6,157,776 describes a heating system for a used cooking oil and grease storage tank. The storage tank described in this prior art patent is typically comprised of a large metal vessel for holding the used cooking oil and grease. While this approach provides a reliable solution for temporarily storing the used cooking oils and grease, the metal storage tanks which are typically comprised of stainless steel or other metals are very expensive. In order to reduce the costs associated with the tanks and the overall recovery process, a variety of alternate solutions have been previously examined.
Previously, for more than 30 years during which used cooking oils have been recovered, stored and recycled, there has been no cooking oil storage tank solution which provides a practical and economical storage tank made from less expensive material such as plastic or polyethylene. Some of the difficulties encountered in the development of such a storage tank include satisfying the requirement that the tank contents be heated during storage in order to provide easy removal of the used cooking oil and grease. The storage tanks of the prior art typically included L-shaped heating members, which required openings in the side wall of the tank which are difficult to implement, when the tank is comprised of a plastic material such as, for example, polyethylene.
Accordingly, there remains a need in the field of cooking oil and grease storage solutions for a more economical storage tank structure. It is therefore one object and advantage of the present invention to provide a practical and economical heated used cooking oil and grease storage tank. It is another object and advantage of the present invention to provide a provide a practical and economical heated used cooking oil and grease storage tank wherein heat is transmitted through the tank so as to maintain all of the grease in a fluid state. Other objects and advantages of the present invention will be apparent in light of the following Summary and Detailed Description of the Presently Preferred Embodiments.